Hydraulic control for motor graders



Nov. 22, 1960 G. E. Ross HYDRAULIC CONTROL FOR MOTOR GRADERS Filed March6, 1958 INVENToR; Cir-:ORGE E. R055 BY @M5015 HTT'Y.

United States Patent O HYDRAULIC CONTROL FOR MOTOR GRADERS George E.Ross, Nevada, Ohio, assignor to The Galion Iron Works & ManufacturingCompany, a corporation of Ohio Filed Mar. 6, 1958, Ser. No. 719,638

1 Claim. (Cl. 60-52) The instant invention relates to motor graders andmore particularly to a novel hydraulic control circuit for operating thevarious devices of the motor grader.

It is the object of this invention to provide a novel hydraulic controlcircuit for a motor grader, in which certain of the devices of thegrader are operated at a constant speed by the hydraulic controlcircuit.

It is another object of the instant invention to provide a novelhydraulic control circuit for a motor grader, in which hydraulic fluidis supplied to a steering valve at a constant rate for operating thesteering means of the grader at a constant speed.

It is a further object of the instant invention to provide a novelhydraulic control circuit for a motor grader, in which hydraulic uid issupplied at a constant rate to a plurality of hydraulic controls for themold lift, the wheel leaning means, the power shift mold board, the plowand the scarier, for operating each of the latter at a constant speed.

It is still another object of the instant invention to provide a novelhydraulic control circuit for a motor grader, in which there is provideda plurality of hydraulic controls for the circle, the side shift, themold lift, the wheel leaning means, the power shift mold board, the plowand the scarier, with the hydraulic fluid being supplied to the circleand side shift hydraulic controls directly from a pump which deliversthe uid from a reservoir tank, and including hydraulic means fordelivering the uid from the circle and side shift hydraulic controls ata constant rate to the hydraulic controls for the mold lift, the wheelleaning means, the power shift mold board, the plow and the scarier, foroperating the latter devices at a constant speed.

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claim.

The drawing herein diagrammatically illustrates the novel hydrauliccontrol circuit for the motor grader.

The instant invention is in a novel hydraulic control circuit for amotor grader, in which the mechanical elements of the grader may be of aconventional form, for example as illustrated in Pat. No. 2,340,169,issued January 25, 1944, for Road Grader. The motor grader includes amold board to which there is attached a blade. The mold board is securedto a circle which may be rotated through 360 for the purpose ofadjusting the angle of the blade. The circle is mounted on a laterallyshiftable frame for adjusting the position of the mold board vlaterallyof the main frame of the motor grader, side shift means being providedfor this purpose.

The mold board may also be shifted laterally with respect to the circlefor extending the mold board and its 'blade to one side or the other ofthe main frame of the motor grader, and for this purpose the power shiftmold Yboard control is provided. The controls for the motor grader alsoinclude a right hand and a left hand mold lift which are utilized toadjust the elevation of one side ICC or the other of the mold board andits blade. The righthand and left hand mold lift controls may also beoperated together to elevate the mold board and blade.

The motor grader includes a pair of wheels at the front end thereof,which may be leaned in one direction or the other, depending on theoperation of the motor grader, for' the purpose of counteracting forceswhich tend to shift the motor grader to one side or the other during theoperation thereof. In conjunction with the leaning of the front wheels,these wheels may be steered for assisting the leaning of the frontwheels in counteracting forcesv which tend to shift the motor grader toone side or the other during the operation thereof. The motor graderalso includes a scan'iier which may be lowered into con-- tact with theground, or raised from the ground so as toz be inactive, and for thispurpose the motor grader con trols include a control for raising andlowering the scari fier. As an accessory device there may be provided a:plow for moving snow or a bulldozer blade, which is at-4 tached at thefront end of the main frame of the grader. A control is provided foroperating the plow, or the bulldozer blade. The plow, or the bulldozerblade, is not. normally attached to the grader, but is added when it isdesired to use either of these devices, there being provided a singlecontrol for one or the other of these.

The above described structure of the motor grader isy conventional, andwill be recognized as such by those skilled in the art. Accordingly,there is not included herein a detailed description of the same, sincethe various devices and the operating means therefor in the motor graderare not of themselves novel, the instant invention being in the hydauliccontrol circuit for controlling the operation of these devices.

Referring to the drawing, the novel hydraulic control circuit comprisesa reservoir tank 1t) which contains a supply of hydraulic uid. A conduit11 leads from the tank 10 to each of a pair of pumps .12, 13 which arearranged in tandem and are driven together from the grader motor,whereby the rate of delivery of hydraulic fluid by the pumps 12, 13 willvary in accordance with the speed of the grader motor. The pump 12supplies hydraulic uid under pressure through conduit 14 for operatingthe steering means of the motor grader. The hydraulic pump 13 supplieshydraulic fluid under pressure through conduit 15 for operating theother devices of the motor grader.

The conduit 14, which leads from the pump 12, includes a relief valve 16which is connected by a conduit 17 to a uid return line 13. Thehydraulic uid is delivered by the line 14 through the pressure reliefvalve 16 to a bypass and restrictor type ow regulator 19, which includesa bypass line 20 connected to the return line 18. The ow regulator 19regulates the How of hydraulic fluid to the steering valve 21, andmaintains the supply of hydraulic tiuid to the valve 21 at a constantrate, irrespective of the rate of delivery of hydraulic fluid by pump12. A pressure relief valve 22 is connected between the flow regulator19 and the return line 1S to relieve any excess pressure in thehydraulic uid delivered to the steering valve 21.

The steering valve 21 is disposed at the operators station of the motorgrader, and is operated by a steering wheel. The steering valve 21 is arotary valve that is operated by rotation of the steering wheel, whichpermits the hydraulic uid to ow through the steering valve for thepurpose of operating the hydraulic steering means, to turn the frontwheels of the motor grader in accordance with the direction in which itis desired to operate the motor grader. The hydraulic uid dischargesfrom the steering valve 21 through the discharge line 18.

The steering valve 21 and each of the other hydraulic controls for the`various operating devices of the motor grader are located at theoperators station on the motor grader and disposed in a manifold 23,indicated diagrammatically by a broken line in the drawing.

The pump 13V delivers hydraulic iluid from the tank through theconduit15'and-through a pressure relief valve 24,-which is connected by Va'line25 to the `fluid return line26. The hydraulicuid that owsthrough therelief valve 24, is directed through the -hydraulic conduit 27 to a bankof hydraulic control valves which control the operation of the variousdevices of the motor grader, as Vis described hereinafter.

The hydraulic conduit 27 delivers-the hydraulic uid under pressure fromthe-pump 13 toa hydraulic controlV valve'28 for controlling theoperation of the circle, and a second hydraulic control valve V29-forcontrolling theoperation ofthe side shift. YThe hydraulic control valves2S,-

29 are secured to each other and the discharge of the valve 28communicates directly with-the intake of the valve 29;` These valves areof a conventional type and each comprises a reciprocable spool mountedWithin the valve casing, which in neutral position permits thehydraulicV fluid to flow freely through the Valve. The spool of each ofthe valves 28, 29 may be reciprocated by means of an operating handle toeither side of the neutral position thereof-for directing the ow ofiluid in one direction or the other. A hydraulic conduit 30 is connectedto the control valve 29 and receives the seepage of hydraulic uid fromthe control valves 28,v 29, and directs this seepage through the conduit26 and the return conduit 31 to the tank 10,.V The hydraulicfluiddischarges from Y theV control valves 28, 29 to a bypass andrestrictor type oW regulator 34 which controls the rate of delivery ofhydraulic fluid to the remaining control valves, by limiting the rate ofdelivery-'of hydraulic fluid to a predetermined maximum. The owregulator 34 is connected Y to the fluid return line 18 by a conduit 35to discharge the surplus of hydraulic uid. Below the ow regulator 34there is a relief valve 36 connected to the seepage conduit 30 for thepurpose of relieving any excessive pressure of the hydraulic uid thatmay occur at this point.

The hydraulic fluid, which is delivered from the ow regulator 34 at apredetermined maximum rate of flow, ows through a bank of six valveseach of which is of the same type and construction as the valves 2S, 29.The valves 38, 39 control the operation of the right hand mold lift andthe left hand mold lift, respectively. The valve 40 controls theoperation of the wheelleaning means, the valve 41 controls the operationof the powerv shift mold board, the valve 42 controls the operation of Ythe snow plow or bulldozer blade, and the valve 43 controls theoperation of the scarifer. As in the case of valves 28, 29, previouslydescribed, each of the valves 38V fluid discharges from the valves 38 to43 through the.y

conduit 45, which directs the ow of hydraulieuid through the returnconduit 31 to the reservoir tank .10.

The various hydraulic control valves 28, 29, 38 to 43, are located atthe operators station of thev motor grader, as part of the manifold 23,and each valve is provided with a handle for reciprocating the spool ofthe valve and, thereby, elfecting a control of the devices of the motorgrader according to the direction in which theiluid flows through thevalve being used at a given time. The hydraulic control Valves 28, 29,38 to 43 may be of any suitable form, for example as illustrated in Pat.No. 2,486,087, issued October 25, 1949, for Hydraulic Valve. The .valves28, 29 are connected to each other for ow of the hydraulic uidtherethrough, and the valves 38 to 43 are similarly connected to eachother for the ow of hydraulic fluid therethrough, which connections maybe made in the manner disclosed in said Pat. No. 2,486,087. Inaccordance with the invention, the rate at which the hydraulic iiuid isdelivered to each of the control valves 38 to 43 is limited to apredetermined maximum, whereby the operating speed of the right and lefthand mold lift, the wheel leaning means, the power shift mold board, thesnow plow or bulldozer blade, and the scariiier is controlled inaccordance with the rate of delivery of hydraulic fluid to the controlvalves 38 to 43. Similarly, the hydraulic uid delivered Vto the steeringvalve 21 is delivered at a constant rate, whereby the operation of thesteering means is at a constant speed. Since vthe hydraulic iiuid foroperating the steering means is delivered by the pump 12 independentlyof the pump 13, which delivers the hydraulic fluid to the other controlvalves, the

speed of operation of the steering means may be different.

from that of the other devices of the motor grader.

Obviously those skilled in the art may make various.

changes in the details and arrangement of parts without departing fromthe spirit and scope of the invention as.

defined by the claim hereto appended, and. applicant therefore wishesnot to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodimentof the invention, what itis desired to secure by ,Letters Patent of the United States is:

In a motor grader comprising a hydraulic control circuit for operating aplurality of individual hydraulic actuators, one hydraulic-actuatorbeing provided for actuation of each of thecircle, the side shift, theright hand. mold lift, the wheel leaning means, the powershift. moldboard,

the plow, the scariier, and the left hand mold lift, `said hydrauliccontrol circuit including a rst bank of open.. center hydraulic controlvalves comprising an individual.

hydraulic control Valve for control ofthe respective hydraulic actuatorfor each of the circle-and theside shift,

and a second bankfof open center hydraulic control valves comprising anindividual hydraulic control valve for control of the respectivehydraulic .actuator for .each of the, right hand mold lift, the YWheelleaning means, the powerV shift mold board, the plow, the scarier, andthe left hand mold lift, a pump for delivering .hydraulic fluid underpressure to the open center vinlet of the first valve bank at a variablerate of ow, a liuid conduit interconnecting the open center outlet ofthe first valve bank to the-open cen` ter inlet of the second valve bankfordirecting the flow kof hydraulic fluid from the rst valve bank to.thesecond valve bank, and a ow regulator valve in the interconnectingconduit means between the rst bank of hydraulic control valves and thesecond bank of hydraulic Vcontrol valves for limiting the rate of flowof hydraulic fluid to..

